Just an FYI - I received the Tumbler and was quite disappointed because both sides of the magnet holder would not hold any knife even reasonably well so that it wouldn't move during sharpening. Even without using the sharping roller even the smallest of knives barely held on, no matter what was its steel composition from high carbon to stainless. I work with magnets daily and I took Gauss meter readings of the Tumbler magnet block and it was quite weak. I sent back the Tumbler for a refund. I was also surprised that Tumbler didn't even comment on the weak magnet issue, or offer a replacement.
Thanks for your video, because A couple of times, I've been tempted to by that knife sharpening out fit and just couldn't believe it was that good for that high price...
It's a cool sharpener but I think I like mine better. It's a simple sharpener that suction cups to your counter and you just drag the knife through it. Inexpensive and works pretty well. Good review, thanks Jeff.